In one example method, a signal transmitted from an endpoint device is received at a first satellite and at one or more second satellites. The first satellite determines a first estimated position of the endpoint, an estimated position of the first satellite, and estimated frequencies and phases of one or more symbols transmitted in the signal. The first satellite then transmits this information to the one or more second satellites. The one or more second satellites use the information received from the first satellite to determine one or more estimated time differences of arrival between the signal arriving at the first satellite and the signal arriving at the one or more second satellites. The one or more second satellites then determine a second estimated position of the endpoint using the one or more estimated time differences of arrival.
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2. The computer-implemented method of claim 1, wherein determining the first estimated time difference of arrival is further based on a first estimated Doppler shift of the estimated frequencies determined at the first satellite and a second estimated Doppler shift of the estimated frequencies determined at the second satellite.
3. The computer-implemented method of claim 2, wherein determining the first estimated time difference of arrival further comprises using the first estimated Doppler shift and the second estimated Doppler shift to solve for an optimal time difference of arrival between the signal arriving at the first satellite and the signal arriving at the second satellite.
5. The computer-implemented method of claim 4, wherein determining the first estimated position of the endpoint comprises using angle-of-arrival information for the signal.
6. The computer-implemented method of claim 5, wherein the angle-of-arrival information for the signal comprises a ratio of beam amplitudes between adjacent receive beams of the first satellite.
7. The computer-implemented method of claim 4, wherein determining the estimated time differences of arrival is further based on estimated positions of the second satellites.
8. The computer-implemented method of claim 4, wherein determining the estimated time differences of arrival is further based on a first estimated Doppler shift of the estimated frequencies determined at the first satellite and second estimated Doppler shifts of the estimated frequencies determined at the second satellites.
10. The computer-implemented method of claim 4, further comprising receiving the estimated time differences of arrival at a ground station, wherein determining the second estimated position of the endpoint is performed using a ground-based computer network.
11. The computer-implemented method of claim 4, wherein determining the second estimated position of the endpoint comprises weighting the estimated time differences of arrival according to respective receive signal strengths of the satellites.
12. The computer-implemented method of claim 4, further comprising time-synchronizing the satellites.
14. The computer-implemented method of claim 13, wherein determining the estimated time differences of arrival and determining the second estimated position of the endpoint are performed using a ground-based computer network.
15. The computer-implemented method of claim 13, wherein determining the first estimated position of the endpoint comprises using angle-of-arrival information for the signal.
16. The computer-implemented method of claim 15, wherein the angle-of-arrival information for the signal comprises a ratio of beam amplitudes between adjacent receive beams of the first satellite.
17. The computer-implemented method of claim 13, wherein determining the estimated time differences of arrival is further based on a first estimated Doppler shift of the estimated frequencies determined at the first satellite and second estimated Doppler shifts of the estimated frequencies determined at the second satellites.
19. The computer-implemented method of claim 13, wherein determining the second estimated position of the endpoint is performed using a ground-based computer network.
20. The computer-implemented method of claim 13, wherein determining the second estimated position of the endpoint comprises weighting the estimated time differences of arrival according to respective receive signal strengths of the satellites.
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December 15, 2023
November 12, 2024
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